1. Field of the Invention
The present invention concerns a method of forming a colored film, a driving device a and liquid crystal display device and, more particularly, it relates to a method of forming a colored film (color filter film) directly to a substrate having an active elements such as a thin film transistor (TFT), a driving device including the colored film and a liquid crystal display device having the driving device.
2. Description of the Related Art
At present, known manufacturing methods for color filters include, for example, (1) a dying method, (2) a pigment dispersing method, (3) a printing method, (4) an ink jet method and (5) an electrodeposition method, which have inherent features and advantages respectively but involve the following drawbacks:
The first dying method requires a photolithographic step for patterning and is poor in light fastness because of the use of a dye and also has a drawback that it requires a number of manufacturing steps.
The second pigment dispersion method also involves a problem of high cost since patterning is conducted by a photolithographic step and a number of steps are required.
The third printing method and the fourth inkjet method require no photolithographic step but the former is poor in the resolution power and the uniformness of the film thickness, while the latter tends to cause color mixing between adjacent filter layers and is poor in view of the resolution power and the positional accuracy.
The fifth electrodeposition method involves a drawback that it requires a patterning step by photolithography such as for forming a common electrode, so that the shape of the pattern is limited and it cannot be used for liquid crystals having TFT.
Further, color filters for liquid crystals cannot generally be used by merely forming a color filter layer and portions between filter cells of respective colors have to be covered with a black matrix, and a photolithographic process is used usually also for the formation of the black matrix, which is one of major factors of cost increase.
Accordingly, it has been demanded for a manufacturing method capable of manufacturing a color filter having a high resolution power and excellent in pattern accuracy, not by way of a photolithographic step, in a simple and convenient step and at low cost. In recent years, a demanded for a display capable of displaying video information and communication information at a high resolution power has increased and a patterned color filter of high fineness has been demanded.
Japanese Published Unexamined Patent Application No. Sho 63-21622 discloses a method of manufacturing a dot matrix type color liquid crystal display device, that is, formation of an RGB color filter in a check pattern by bringing an external electrode selectively into contact with a display electrode of a substrate on the side of an active matrix and electrodepositing a dye on the surface of the display electrode, as a deposited electrode, in contact with the external electrode. Japanese Published Unexamined Patent Application No. Hei 2-153325 discloses a method of manufacturing a display electrode of an active matrix type color liquid crystal display device by forming thin film transistors and color filter forming electrodes corresponding to the thin film transistors respectively on an insulative substrate, then forming a color filter by using the color filter forming electrodes by electrodeposition and forming liquid crystal driving pixel electrodes connected with the thin film transistors on the color filter. Japanese Published Unexamined Patent Application No. Hei 5-257137 discloses a color liquid crystal display device in which a display electrode substrate having plural display electrodes formed on the surface of a first glass substrate and a common electrode substrate having a common electrode formed on the surface of a second glass substrate are opposed to each other by way of liquid crystals, wherein a colored layer is formed by an electrodeposition method on each of the display electrodes.
Japanese Published Unexamined Patent Application No. Hei 10-324994 describes formation of a color filter having mixed color images constituted with a group of pigments on a first electrode in which a relatively low DC voltage at 0.6 to 3.0 V is applied between a first electrode in contact with (or immersed in) an aqueous solution containing dissolved therein two or more of dyes each of an identical polarity containing at least one kind of a dye capable of being deposited solely from the state dissolved in an aqueous solution by electrochemical reactions in a coexistent state at a specified pH value and a second electrode disposed such that the electrochemical reaction can be taken place in cooperation with the first electrode, thereby forming a color filter having mixed color images constituted with the group of dyes on the first electrode. Japanese Published Unexamined Patent Application No. Hei 11-133224 describes formation of a color filter by forming a transparent conductive film on a transparent substrate, and forming thereon an organic or inorganic semiconductor film to form a substrate, preparing an aqueous solution containing an electrodeposition material including a colorant, a dye chemically dissolving or depositing/precipitating depending on the pH change and a water soluble dispersible polymer in a vessel capable of storing a liquid, fixing the substrate that connects a device capable of supplying a current or an electric field with the transparent conductive film such that the thin semiconductor film is immersed in the aqueous solution, disposing a counter electrode as the other of the electrode pair in the aqueous solution and irradiating the substrate thereby depositing an electrodeposition film containing the deposition material selectively to a portion where an electromotive force is generated by the irradiation of light. According to this patent publication, a simple glass substrate is disclosed as the substrate. Further, Japanese Published Unexamined Patent Application No. Hei 11-350193 laid-open after the filing date of this invention in Japan discloses disposing a substrate formed by successively laminating a support, a conductive film and a thin semiconductor film such that at least the thin photosemiconductor film is in contact with the electrolyte, supplying a current or a voltage to the conductive film and irradiating the substrate from the side of the thin photosemiconductor film by way of the electrodeposition solution and selectively generating photoelectromotive force to the irradiated area of the photosemiconductor film thereby forming an electrodeposition film to the irradiated area. In the same manner, Japanese Published Unexamined Patent Application No. Hei 2000-28821 laid-open after the filing date of the present invention in Japan discloses preparation of a filter by immersing, into an electrodeposition solution containing a coloring electrodeposition material, at least a photosemiconductor film of an electrodeposition substrate formed by disposing a transparent thin conductive film and a thin photosemiconductor film having a photovoltaic function in this order on a transparent support, supplying a voltage or current to the conductive film, image-exposing the electrodeposition substrate to form a colored electrodeposition film in an irradiated area and, finally, supplying a current in the state where the electrodeposition substrate is in contact with a metal plating solution thereby forming a black matrix film by metal plating.
By the way, since the liquid crystal display device generally has a structure of using a TFT driving substrate having thin film transistors (TFT), sandwiching liquid crystal materials between the TFT driving substrate and an RGB color filter substrate by way of a transparent conductive film, and controlling the transmissivity of a light to an RGB color filter by ON/OFF control for the application of the voltage to the transparent conductive film, both of the TFr driving substrate and the color filter substrate are required, resulting in increasing the manufacturing cost. That is, since the TFT driving substrate and the color filter substrate are manufactured separately in different manufacturing processes, it has been difficult to reduce the cost for the liquid crystal display device including them in combination.
Further, as described above, since the manufacturing processes are different, it has been difficult for final positioning between both of them and there has been also a problem in view of the stable production of liquid crystal display devices of high resolution power.
As has been described above, it has not yet been provided a method and a driving device capable of manufacturing a liquid crystal display device of high resolution power stably and at low cost, not based on the combination of the TFT. driving substrate and the color filter manufactured separately.
The present invention dissolves various problems in the prior art and provides a method of forming a colored film by simple and convenient steps and at low cost in which a colored film including a fine pixel pattern of high resolution power and excellent in surface smoothness directly on a substrate having an electronic circuit material.
The present invention further provides a driving device having a colored film of high resolution power and excellent in surface smoothness at low cost.
The present invention further provides a liquid crystal display device having a fine pixel pattern of high resolution power, not based on the combination of a TFT driving substrate and a color filter manufactured separately.
The present invention further provides a method of manufacturing a colored deposition film giving less effect on a driving device when forming a colored film by electrodeposition to the substrate on the driving side of a liquid crystal display device, as well as provides a method of manufacturing a color filter capable of arranging filter of respective RGB colors easily in a check pattern upon manufacture of the RGB color filter.
Some aspects of the present invention are as follows:
 less than 1 greater than  A method of forming a colored film including:
a step of forming a substrate for electrodeposition by laminating at least a transparent conductive film and a transparent thin photosemiconductor film having a photovoltaic function in this order on the surface of a substrate having a thin film transistor on a transparent support, and
a step of irradiating with a light at least a light photosemiconductor film of the substrate for electrodeposition while bringing the same into contact with an aqueous electrolyte containing an electrodeposition material containing a colorant, thereby selectively a generating photoelectromotive force to an irradiated area of the thin photosemiconductor film and electrochemically depositing the electrodeposition material to form a colored film.
 less than 2 greater than  A method of forming a colored film according to one aspect of the present invention, wherein the step of forming a substrate for electrodeposition is a step of forming a conductive film so as to be joined with the electronic circuit material in a region on the surface of the substrate on the side disposed with the thin film transistor in which the electronic circuit material is not disposed and laminating the thin photosemiconductor film at least on the conductive film thereby forming the substrate for electrodeposition.
 less than 3 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the step of forming a substrate for electrodeposition is a step of disposing a transparent insulative layer on the surface of the substrate and then laminating at least a conductive film and a thin photosemiconductor film in this order.
 less than 4 greater than  A method of forming a colored film according to another aspect of the present invention constituting, after the step of forming a colored film, a step of forming a transparent conductive layer on the surface of the substrate for electrodeposition on the side formed with the colored film, so as to have a current supply channel relative to an electronic circuit material.
 less than 5 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the volume electric resistance value of the colored film is from 1031 3 to 1012xcexa9xc2x7cm.
 less than 6 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the thickness of the colored film is from 0.4 to 4.5 xcexcm.
 less than 7 greater than  A method of forming a colored film according to another aspect of the present invention, constituting, after the step of forming a colored film, a step of heat treating at a temperature from 80 to 250xc2x0 C.
 less than 8 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the electrodeposition material contains a compound having carboxyl groups.
 less than 9 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the compound having the carboxyl groups is a polymer having hydrophobic domains and hydrophilic domains and the number of the hydrophobic domains is 30 to 75% of the total number of the hydrophobic domains and the hydrophilic domains.
 less than 10 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the hydrophobic domain in the polymer includes a styrene or styrene derivative.
 less than 11 greater than  A method of forming a colored film according to another aspect of the present invention, wherein 50% or more for the number of hydrophilic domains in the polymer changes from a water-soluble state to a water-insoluble state or from a water-insoluble state to a water-soluble state depending on the change of pH.
 less than 12 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the acid value of the polymer is from 60 to 200.
A method of forming a colored film according to another aspect of the present invention wherein the acid value of the polymer is from 70 to 130 is preferred.
 less than 13 greater than  A method of forming a colored film according to another aspect of the present invention, wherein the number average molecular weight of the polymer is from 6,000 to 25,000.
A method of forming a colored film according to another aspect of the present invention wherein the number average molecular weight of the polymer is from 9000 to 20,000 is preferred.
 less than 14 greater than  A method of forming a colored film according to another aspect of the present invention, wherein an ion dissociation salt not giving an effect on the electrodeposition characteristic is added to an aqueous electrolyte to make the volume resistivity of the aqueous electrolyte to 100 to 105 xcexa9xc2x7cm in the step of forming a colored film.
 less than 15 greater than  A method of forming a colored film according to another aspect of the present invention, wherein pH of the aqueous electrolyte is within a range of xc2x11.5 relative to pH at which the electrodeposition material starts deposition and 8.5 or less.
 less than 16 greater than  A driving device having, on a transparent support, an electronic circuit material, a transparent conductive film connected with the electronic circuit material, a transparent thin photosemiconductor film having a photovoltaic function and covering at least the conductive film, and a colored film disposed on the thin photosemiconductor film.
A driving device further having a transparent conductive layer on at least the colored film is preferred.
 less than 17 greater than  A driving device including, on a transparent support, plural thin film transistors arranged orderly, a first common electrode connecting gate electrodes constituting respective thin film transistors in common, a second common electrode connecting source electrodes constituting respective thin film transistors in common, a transparent conductive film connected with drain electrodes constituting respective thin film transistors, a transparent thin photosemiconductor film having a photovoltaic function and covering at least the conductive film, and a colored film disposed on the thin photosemiconductor film.
A driving device further having a transparent conductive layer on at least the colored film is preferred.
 less than 18 greater than  A liquid crystal display device including a driving device according to another aspect of the present invention, a transparent conductive plate disposed being opposed to the driving device, and a liquid crystal material disposed between the driving device and the transparent conductive plate.